1. Field of the Invention
This invention relates to N-3,3-dimethylbutyl-L-aspartic acid and derivatives thereof. The invention also relates to a process for preparing N-[N-(3,3-dimethylbutyl)-L-.alpha.-aspartyl]-L-phenylalanine 1-methyl ester (neotame) via peptide coupling of a derivative of the novel N-(3,3-dimethylbutyl) L-aspartic acid with L-phenylalanine or an L-phenylalanine ester.
2. Related Background Art
N-[N-(3,3-dimethylbutyl)-L-.alpha.-aspartyl]-L-phenylalanine 1-methyl ester (neotame) is a highly intense non-nutritive sweetening agent useful to impart sweetness to a wide variety of food products. This sweetener, disclosed in U.S. Pat. No. 5,480,668, is approximately 8,000 times as sweet as sucrose, on a weight basis. Thus, very small quantities of this sweetening agent may be used to produce foods and food products that are equi-sweet tasting to presently available high caloric food products.
U.S. Pat. No. 5,510,508 describes a method for preparing N-[N-(3,3-dimethylbutyl)-L-.alpha.-aspartyl]-L-phenylalanine 1-methyl ester of the formula ##STR1## comprising treating an aqueous acetic acid/alcoholic solution of aspartame and 3,3-dimethylbutyraldehyde, at room temperature, with hydrogen at a pressure less than or equal to 1 bar (0.1 MPa) in the presence of a catalyst based on platinum or palladium. The product is purified by precipitation and filtration after the alcohol is removed from the solution under vacuum.
U.S. Pat. No. 5,728,862 describes a method comprising treating a solution of aspartame and 3,3-dimethylbutyraldehyde in an organic solvent with the reducing agent, hydrogen in the presence of a catalyst. After removal of the catalyst, water is added to form an aqueous/organic solvent solution containing about 17% to about 30% of the organic solvent, by weight, from which the neotame is obtained by precipitation and filtration.
It would be desirable, however, to develop more efficient and cost-effective methods of preparing high-purity neotame from readily available or readily obtainable materials.